I feel the answer is D. to learn to be an American. This is true so they would be American in character and for their nationality.
In a feudal system, a vassal, akin to a serf in most contexts, in general worked land on a lord's fiefdom in exchange for some of the produce from the land and some military protection.
Economics was the main reason why most immigrants opted to settle in the North rather than in the South. Majority of the immigrants who came to America had little money so they had to find jobs immediately. There were plenty of factories and mining jobs available. Work in the South consisted more on farming. Also, immigrants did not want to work in slave states where they would have to compete with unpaid slaves.
The answer is A the natives land was given to the encomenderos
I think its the the Sherman Anti-Trust Act